Off road vehicle with air intake system

ABSTRACT

An off-road vehicle includes a frame and a plurality of wheels. An engine powers the wheels. An air intake system supplies air to the engine. The air intake system has an air inlet through which ambient air enters the intake system. The air inlet is positioned higher than the wheels. An air intake duct extends rearward to the engine from the air inlet. At least a portion of the air intake duct is positioned lower than the tops of the wheels.

PRIORITY INFORMATION

The present application is based on and claims the benefit under 35U.S.C. § 119(e) of U.S. Provisional Application Nos. 60/459,958 and60/460,068, both filed on Apr. 2, 2003, the entire contents of which ishereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an air intake system for anoff-road vehicle.

2. Description of Related Art

Off-road vehicles are designed to be operated over rugged terrain. Thesevehicles are often operated on unpaved terrain such as, for example,steep inclines and declines, rough roads, and areas covered in mud andwater.

The off-road vehicles typically include a frame that is supported bywheels. In one common arrangement, the vehicle has four wheels, i.e., apair of front wheels and a pair of rear wheels. An internal combustionengine is employed to power at least the rear or front wheels, and mostcommonly, all of the wheels. Typically, the engine is combined with atransmission to form an engine unit. The transmission transfers power toan output shaft from a crankshaft of the engine. The output shaft drivesthe wheels through a drive mechanism. The off-road vehicle has a seatunit on which a driver and/or a passenger sit.

The engine typically has an air intake system through which ambient airis supplied to the engine. The intake system can include an air cleanerthat filters the air before it is delivered to the combustion chamber(s)of the engine. For example, Japanese Patent Publication No. 2000-103246discloses an off-road vehicle having such an air cleaner. The aircleaner disclosed in the publication is positioned lower than a topsurface of the seat unit. Thus, the air cleaner is likely to draw waterwhen the wheels are submerged.

SUMMARY OF THE INVENTION

One aspect of the present invention involves an off-road vehiclecomprising a frame. A plurality of wheels is arranged to support theframe. An internal combustion engine powers at least one of the wheels.An air intake system is arranged to supply air to the engine at alocation higher than an uppermost surface of the wheels. The air intakesystem has an air inlet through which ambient air enters the intakesystem. The air inlet is positioned higher than the wheels and an airintake duct extends rearward to the engine. At least a portion of theair intake duct is positioned lower than the uppermost surface of thewheels.

In accordance with another aspect of the present invention, an off-roadvehicle comprises a frame. A plurality of wheels is arranged to supportthe frame. A hood is configured to cover at least a first portion of theframe. An internal combustion engine powers at least one of the wheels.An air intake system is arranged to supply air to the engine. The airintake system comprises an air cleaner configured to clean the air. Theair cleaner is disposed below a center portion of the hood.

In accordance with a further aspect of the present invention, anoff-road vehicle comprises a frame. A plurality of wheels is arranged tosupport the frame. At least two seat assemblies are disposed side byside on the frame. An internal combustion engine powers at least one ofthe wheels. An air intake system is arranged to supply air to theengine. The air intake system comprises an air cleaner configured toclean the air. At least a portion of the air cleaner is positionedbetween the seat assemblies.

Another aspect of the present invention involves an off-road vehiclecomprising a frame and a plurality of wheels arranged to support theframe. At least one seat is supported by the frame. An internalcombustion engine powers at least one of the wheels, and an air intakesystem is arranged to supply air to the engine. The air intake systemcomprising an air cleaner that filters air supplied at least to theengine. The seat is disposed in a fore to aft direction on the vehiclesuch that the air cleaner lies forward of the seat and at least aportion of the engine lies to the rear of the seat.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features, aspects and advantages of the presentinvention are described in detail below with reference to the drawingsof a preferred embodiment which is intended to illustrate and not tolimit the invention. The drawings comprise twelve figures in which:

FIG. 1 is a side elevational view of an off-road vehicle configured inaccordance with certain features, aspects and advantages of the presentinvention;

FIG. 2 is a top plan view of the off-road vehicle of FIG. 1;

FIG. 3 is a schematic side elevational view of the off-road vehicleshowing at least an engine unit, a seat and a portion of an air intakesystem;

FIG. 4 is a partial cross-sectional of the off-road vehicle taken alongthe line 4-4 of FIG. 2;

FIG. 5 is a schematic top plan view of the engine unit of FIG. 3;

FIG. 6 is a schematic side elevational view of the engine unit and theseat, as well as a portion of a framework of the off-road vehicle thatextends next to the engine unit and the seat, and also illustrates amodified air inlet duct shown in phantom;

FIG. 7 is a schematic top plan view of the engine unit, the seat and theportion of the off-road vehicle framework shown in FIG. 6;

FIG. 8 is a top plan view of an air outlet duct with a portion of theseat shown in phantom;

FIG. 9 is a rear view of the air outlet duct of FIG. 8 with a portion ofthe seat shown in phantom.

FIG. 10 is a schematic side elevational view of the engine unit, theseat and a modified air intake system;

FIG. 11 is a top plan view of a rear portion of a modified off-roadvehicle that includes another type of an exhaust system; and

FIG. 12 is a side elevational view of the rear portion of the off-roadvehicle illustrated FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1-7, an overall construction of an off-roadvehicle 30 is described. While the embodiment is described in connectionwith this particular type of vehicle, those of skill in the art willappreciate that certain features, aspects and advantages of the presentinvention may have utility in a wide range of applications for othervehicles, for example, with snowmobiles, tractors, utility vehicles andthe like.

With reference to FIGS. 1, 2 and 4, the off-road vehicle 30 preferablyhas an open tubular-type frame 32. The illustrated frame 32 comprises amain frame section 34, a front frame section 36, a rear frame section 38and a compartment frame section (or pillar frame section) 40.

The main frame section 34 includes a pair of side frame units 42 spacedapart side by side with each other. Each side frame unit 42 comprises afront tubular member 42 a (FIG. 2) and a rear tubular member 42 b (FIG.2). Each tubular member 42 a, 42 b preferably is rectangularly formed insection, but other configurations cal also be used. In one variation,the front and rear members 42 a, 42 b can have a circular shape insection. Moreover, the members 42 a, 42 b can have an incomplete tubularshape such as, for example, a U-shape. A rear end of the front tubularmember 42 a is bent outwardly and is coupled with a mid portion of therear tubular member 42 b. A forward end of the rear tubular member 42 bis bent inwardly and is coupled with a mid portion of the front tubularmember 42 a. Thus, in the illustrated arrangement, both of the front andrear tubular members 42 a, 42 b are nested together. The side frameunits 42 preferably are connected together by front, center and rearcross members 44 (FIG. 2) that transversely extend between the tubularmembers 42 a, 42 b.

The front frame section 36 extends generally upward from a front portionof the main frame section 34. The rear frame section 38 also extendsgenerally upward from a rear portion of the main frame section 34. Therear frame section 38 preferably includes a pair of rear frame members46 (FIG. 2). Several struts connect the rear frame members 46 to theside members 42 of the main frame section 34 and support the rear framemembers 46 above the side members 42.

The compartment frame section 40 is disposed generally between the frontand rear frame sections 36, 38 in a side view as shown in FIG. 1. Thecompartment frame section 40 includes a pair of compartment members (orpillar members) 48 extending generally upward and higher than the frontand rear frame sections 36, 38. The compartment members 48 are spacedapart from each other on both sides of the off-road vehicle 30 to beplaced more outward than the main frame section 34 in the illustratedembodiment.

A floorboard or floor panel 50 extends in an area generally defined bythe compartment members 48 in a top plan view as shown in FIG. 2 and isaffixed at least to the main frame 34. The floorboard 50 defines apassenger compartment together with the compartment frame section 40. Asbest shown in FIG. 4, the illustrated floorboard 50 generally is a flatpanel with a portion that projects upward. That is, the floorboard 50comprises a horizontal section 51 defining a generally flat area and aprojection 52 defining a tunnel extending along a longitudinal centerplane LC (FIG. 2) of the frame 32 that extends vertically and fore toaft. The horizontal section 51 can support feet of a driver and apassenger and also can be used as a step when the driver or thepassenger enters or leaves the passenger area of the off-road vehicle30. The illustrated projection 52 is trapezoidally configured in sectionand thus has slanted side surfaces 53 and a top surface 54. Otherconfigurations can also be used.

The main, front, rear and compartment frame sections 34, 36, 38, 40preferably are welded to each other. The illustrated structure andarrangement of the frame 32, and the combination of the frame 32 and thefloorboard 50 are merely one example. Various structures, arrangementsand combinations other than those are practicable. For instance, therespective frame sections 34, 36, 38, 40 can be provided with struts orreinforcement members that are not described above.

With reference to FIGS. 1 and 2, the off-road vehicle 30 preferably hasa pair of front wheels 56 and a pair of rear wheels 58 those of whichtogether support the frame 32. Each wheel 56, 58 preferably has aballoon tire (i.e., a tube-less tire) to advantageously proceed overrough roads and in mud and water. Preferably, the balloon tire isrelatively wide and air pressure of the tire is relatively high. In onearrangement, the selected balloon tires are sized as follows: 25×8-12 atthe front end and 25×10-12 at the rear end.

The front and rear wheels 56, 58 preferably are coupled with the frame32 through front suspension mechanisms 60 and rear suspension mechanisms62, respectively. Each front suspension mechanism 60 swingably (up anddown) and independently suspends the associated front wheel 56. Eachrear suspension mechanism 62 also swingably (up and down) andindependently suspends the associated rear wheel 58. Thus, theillustrated off-road vehicle 30 preferably features four wheelindependent suspension.

With reference to FIGS. 1-3, 6 and 7, the off-road vehicle 30 preferablyhas a seat unit 66. The illustrated seat unit 66 comprises a pair ofseats 68 on which the driver and the passenger can sit. The seats 68preferably are disposed side by side. The rear frame section 38, atleast in part, forms a pair of seat pedestals (not shown). Each seat 68and each seat pedestal together form a seat assembly. The illustratedoff-road vehicle 30 thus has two seat assemblies. The seat assembliesare spaced apart from each other to form a space 70 (FIG. 2)therebetween. Through this description, the term “seat unit” may includethe space 70 in the broad sense.

A preferable construction or structure of an off-road vehicle similar tothe off-road vehicle 30 is disclosed in, for example, co-pending U.S.application Ser. No. 10/791,111 filed on Mar. 2, 2004, titled “ENGINEARRANGEMENT FOR OFF-ROAD VEHICLE,” co-pending U.S. application Ser. No.10/791,353 filed on Mar. 2, 2004, titled “DRIVE SYSTEM FOR OFF-ROADVEHICLE,” co-pending U.S. application Ser. No. 10/790,932 filed on Mar.2, 2004, titled “AIR INTAKE SYSTEM FOR OFF-ROAD VEHICLE,” and co-pendingU.S. application Ser. No. 10/792,463 filed on Mar. 2, 2004, titled“FLOOR ARRANGEMENT FOR OFF-ROAD VEHICLE,” the entire contents of whichare hereby expressly incorporated by reference.

In this description, the terms “front” and “forward” mean the directionin which the driver or passenger looks straight when seated on the seats68. Also, the terms “rear,” “rearward” and “backward” mean the directionopposite to the front direction.

Each seat 68 preferably comprises a seat cushion 72 and a seat back 74.The seat cushion 72 extends generally horizontally over the seatpedestal and is detachably or removably affixed to the seat pedestal.The seat back 74 extends generally vertically and upward from a rearportion of the seat cushion 72. In the illustrated arrangement, the seatcushion 72 and the seat back 74 are formed unitarily. In one variation,the seat cushion 72 and the seat back 74 can be separately formed andassembled together.

With reference to FIG. 3, the illustrated seat unit 66 has a forward end78, a rear end 80 and a top end 82. In this arrangement, the forward end78 of the seat unit 66 is defined by forward ends of the seat cushions72. If, however, the seat pedestals extend forward of than the seatcushions 72, forward ends of the seat pedestals can define the forwardend of the seat unit 66. An imaginary forward, generally vertical plane84 can be defined through the forward end of the seat unit 68.

The rear end 80 and the top end 82 preferably are defined by rear endsof the seat backs 72 and top ends of the seat backs 74, respectively. Animaginary rearward, generally vertical plane 86 can be defined throughthe rear ends of the seat backs 74. Also, an imaginary, generallyhorizontal plane 88 can be defined through the top ends 82 of the seatbacks. The seat 68, however, can be shaped in various configurations.The seat back 74 may be omitted under some circumstances. If the seatback 74 is omitted, the imaginary rear, generally vertical plane 86 canbe defined more forwardly as indicated by the reference numeral 86A.Furthermore, the rear, generally vertical plane 86 may be defined moreforwardly as indicated by the reference numeral 86B if the thickness ofthe seat back 74 is reduced. Also, the generally horizontal plane 88 maybe shifted downward to a top surface 72 a of each of the seat cushions72 as indicated by the reference numeral 88A.

In the illustrated embodiment, the top surface 72 a of each seat cushion72 undulates and has a recessed portion 72 aR that is positioned lowerthan the horizontal plane 88A just in front of the seat back 74. Thedriver or the passenger sits in the recessed portion 72 aR of therespective seat 68.

Thus, the forward, rear and top ends 78, 86, 82, the imaginary forwardand rear generally vertical planes 84, 86 and the imaginary generallyhorizontal plane 88 are normally determined depending on a configurationof the seat assembly, which includes the seat 68 and the seat pedestalin the illustrated arrangement. More practically, the rear end 86 shouldbe substantially on the imaginary, generally vertical forward plane 86Aor the imaginary, generally vertical rear plane 86B. Also, the top end82 should be substantially the upper-most end of the seat cushions 72and should be on the imaginary, generally horizontal plane 88A. Becausethe seats 68 are positioned on the seat pedestals which have a certainheight, a relatively large space is formed lower than the imaginary,generally horizontal plane 88A.

The seat unit 66 can have other number of seats such as, for example,three seats in some alternative arrangements. The seats 68 can be madeof any soft materials such as, for example, but without limitation,cloth, rubber, sponge or styrene foam. Further, the seats 68 can be madeof hard materials rather than the soft materials. For example, metal,hard plastic or wood can be used.

With reference to FIGS. 6 and 7, the respective compartment members 48on both sides preferably have an arm rest 90, although only the arm rest90 on the left-hand side is illustrated. Each arm rest 90 preferably isaffixed to a portion of each compartment member 48 for pivotal movementabout a pivot axis that extends transversely relative to the associatedcompartment member 48. The arm rest 90 thus can move between a fullyextended position (illustrated by solid lines in the figures) and afully retracted position (illustrated by phantom lines in the figures).The arm rest 90 can be held generally horizontally when the arm rest 90lies in the fully extended position. On the other hand, the arm rest 90can generally extend parallel to the compartment member 48 when the armrest 90 lies in the fully retracted position. The driver or thepassenger (or both) can place one of his or her arm(s) on the arm restwhile sitting on the seat(s) 68.

Additionally, conventional seat belts (not shown) such as, for example,three-point retaining type seat belts can hold the driver and thepassenger in an appropriate position on the seats 68. Metal fittingsthat fix the seat belts preferably are positioned in the compartmentarea defined by the compartment frame 40 such that the fittings cannotbe caught by branches or twigs of trees while the off-road vehicle 30proceeds in a forest or woods. In other words, the metal fittingspreferably are not exposed out of the compartment area.

With reference to FIGS. 1 and 2, the off-road vehicle 30 preferably hasa carrier or cargo box 92 behind the seat unit 66. The illustratedcarrier 92 extends over a rear portion of the rear frame section 38 andis suitably affixed at least to the rear frame members 46. In onearrangement, the carrier 92 can be tipped rearward to allow its contentsto be dumped. The carrier 92 preferably is formed generally in the shapeof a rectangular parallelepiped and has a bottom, a front, a rear, and apair of lateral sides. That is, the carrier 92 is generally configuredas an open-topped box.

The bottom of the carrier 92 preferably comprises steps 96 on both sidessuch that side portions 98 of the bottom are positioned higher than acenter portion 100 of the bottom. The steps 96 advantageously reduce thelikelihood that the rear wheels 58 will contact the carrier 92 when therear wheels 58 are in an uppermost position of the suspension travel. Itshould be noted that the described movement of the rear wheels 58 is therelative movement thereof in relation to the carrier 92. The centerbottom portion 100 thus increases the capacity of the carrier 92. Each96 preferably extends fore to aft as shown in FIG. 2. Longitudinallyshortened steps (similar to wheel wells) also can be used.

The center bottom portion 100 helps lower the center of gravity of thecarrier 92. The illustrated off-road vehicle 30 thus features enhancedstability. The steps 96 also reduce lateral movement of loads.Additionally, the manufacture of the carrier 92 is simple and costeffective because the steps 96 only extend fore to aft. The steps 96also can increase the stiffness of the carrier 92.

With reference to FIGS. 1 and 2, the off-road vehicle 30 comprises asteering system 104. The steering system 104 in the illustratedembodiment includes a steering wheel 106 and a steering shaft unit 110.The steering shaft unit 110 is disposed on the frame 32 for steeringmovement in front of the seat 68, which is located on the left-hand sideof the illustrated off-road vehicle 30.

The illustrated steering shaft unit 110 comprises an upper steeringshaft 116 and a lower steering shaft 118 both pivotally affixed to theframe 32. The upper shaft 116 extends generally upward and is inclinedrearward toward the driver's area. The steering wheel 106 is affixed tothe top end of the upper shaft 116. The driver thus can operate thesteering wheel 106 while seated on the seat 68. The lower shaft 118extends toward the other part of the steering system 104. The other partof the steering system 104 is structured to direct the front wheels 56right or left relative to the longitudinal center plane LC of the frame32 in response to the steering movement of the steering wheel 106. Theother part of the steering system 104 preferably includes a pair oftie-rods (not shown) coupled to both the front wheels 56 and arack-and-pinion assembly (not shown) connecting the lower shaft 118 withthe tie-rods (not shown). The rack-and-pinion assembly in theillustrated embodiment is disposed on a front differential gear unit119, which will be described below.

Preferably, an inclination angle of the upper steering shaft 116 isadjustable such that a position of the steering wheel 106 can be movedto fit various heights of drivers. For example, a ratchet-type tiltdevice can be used to adjust the inclination angle of the upper steeringshaft 116.

With reference to FIGS. 1 and 2, a hood or bonnet 120 preferably coversa front portion of the frame 32. Preferably, the hood 120 comprises atop surface section, a front surface section and a pair of lateral sidesections. Those sections can be unitarily formed with a piece of sheetmetal and can be made in, for example, a press process. In onevariation, separate pieces of the sections can be affixed together, forexample, by welding. Other materials such as, for example, a plasticmaterial can be used. Also, other conventional manners can be applied toproduce the hood 120.

As thus constructed, the illustrated hood 120 covers the main framesection 34, the front frame section 36, the front wheels 56 and a majorportion of the steering system 104. A dashboard 122 preferably dependsfrom a rear end of the hood 120 and faces the passenger compartment. Ameter unit 124 is disposed in a center area of the dashboard 122. Themeter unit 124 preferably incorporates meters and/or gauges such as, forexample, a speedometer, a fuel level meter and the like. Because of thismeter unit arrangement, the driver can easily view the individual metersat a glance.

The top surface section of the hood 120 preferably inclines downwardtoward the front surface section of the hood 120. The hood front surfacesection extends downwardly (preferably in a generally vertical manner)from the top surface section of the hood. A front bumper 126 extendsfrom the side frame units 42 forwardly and upwardly to protect the frontsurface section of the hood 120.

A radiator or heat exchanger 128 preferably is disposed between thefront surface section of the hood 120 and the front frame section 36.The radiator 128 can be used to cool coolant (e.g., water) that is usedin a cooling system. The radiator 128 can be affixed to the front framesection 36. The radiator 128 preferably has a fan 130 to cool heatedcoolant that flows through the radiator 128.

A battery 132 is preferably disposed under the hood 120 and generallybehind the radiator 128. The battery 132 can be placed on a stay orbracket extending from the front frame section 36 and can be affixed tothe stay or bracket in a proper manner. The illustrated buttery 132 ispositioned above the front differential gear unit 119. At least a topsurface of the battery 132 is positioned at almost the same elevation asthe seat cushions 72 in the illustrated arrangement.

The above-described position of the battery 132, which has significantweight, improves the weight balance of the off-road vehicle 30. That is,the center of the gravity of the off-road vehicle 30 can be shiftedforward by spacing the battery 132 well apart from an engine unit of theoff-road vehicle, which preferably is disposed between the seats 68 asdescribed shortly. The battery 132 in this location also can be cooledby the fan 130 of the radiator 128. Moreover, because at least the topof the battery 132 is positioned at almost the same elevation as theseat cushions 72, the battery 132 is less likely to be submerged inwater even when the wheels 56, 58 are submerged. Further, no space isnecessary for the battery 132 under or around the seats 68. Thus, thespace under or around the seats 68 can be used for placing other largecomponents such as, for example, a fuel tank and a luggage box, as wellas can be used for other for other purposes.

With reference to FIGS. 1-5, the off-road vehicle 30 has a prime moverthat powers the off-road vehicle 30 and particularly the front and rearwheels 56, 58. The prime mover preferably is an internal combustionengine 142. Alternatively, an electric motor can replace the engine 142.Engine power is transferred to the front and rear wheels 56, 58 througha suitable transmission 144 and a suitable drive system 146. In theillustrated arrangement, the engine 142 and the transmission 144 arecoupled together to form the engine unit, which now is indicated by thereference numeral 148. The engine 142 includes foregoing cooling systemmentioned above.

The illustrated transmission 144 advantageously includes an endlessV-belt transmission mechanism 144 a and a switchover mechanism 144 b.The illustrated drive system 146 comprises a forward driveshaft 150extending forward from the engine unit 148, a rear driveshaft 152extending rearward from the engine unit 148. A front differential gearunit 119 is coupled with the front axles (not shown) of the front wheels56, and a rear differential gear unit 154 is coupled with the rear axles(not shown) of the rear wheels 58. In some arrangements, a single axlecan replace the half axles.

The forward driveshaft 150 preferably extends through the tunnel definedby the projection 52 of the floorboard 50. In other words, the forwarddriveshaft 150 is positioned under the top surface 54 of the projection52 of the floorboard 50 and is positioned higher than the horizontalsection 51 of the floorboard 50. In this position, the forwarddriveshaft 150 is less likely to be hit by rocks, wooden blocks or thelike.

The engine unit 148 preferably is positioned generally in the space 70defined between the seat assemblies. The illustrated engine 142 operateson a four-stroke combustion principle; however, other operatingprinciples can be used (e.g., 2 stroke and rotary). The engine 142preferably has a single cylinder block 158 that extends generally upwardand rearward from a lower section of the engine unit 148. That is, thecylinder block 158 has a cylinder axis CA that inclines relative tovertical at a certain angle. The illustrated cylinder axis CA inclinesfrom vertical at approximately 45 degrees.

In the illustrated arrangement, the engine 142 is an internal combustionengine. As such, the cylinder block 158 preferably defines a cylinderbore (not shown) therein. A piston (not shown) is reciprocally disposedwithin the cylinder bore (not shown). A cylinder head 160 preferablycloses an upper end of the cylinder bore to define, together with thecylinder bore and the piston, a combustion chamber 163.

The cylinder head 160 also defines a pair of intake ports 162 and a pairof exhaust ports 166 that communicate with the combustion chamber 163.An intake valve can be provided at each intake port 162 to selectivelyopen the combustion chamber 163 to an air intake system 164. In theillustrated arrangement, the air intake system 164 is coupled with theintake ports 162 at a front surface 165 of the cylinder head 160. Thefront surface 165 of the cylinder head 160 preferably is disposedsubstantially within the space 70 and preferably faces generally forwardand upward. With reference to FIG. 2, the front surface 165 desirably isdisposed generally between the seats 68.

The air intake system 164 introduces air into the combustion chamber 163through the intake ports 162 when the intake valves (not shown) open thepassage into the combustion chamber 163. An exhaust valve (not shown)also is provided at each exhaust port 166 to selectively open thecombustion chamber 163 to an exhaust system 168. In the illustratedarrangement, the exhaust system 168 is coupled with the exhaust ports166 at a rear surface 169 of the cylinder head 160. The rear surface 169of the cylinder head 160 is positioned substantially opposite to thefront surface 165 and generally faces rearward and downward. The exhaustsystem 168 routes exhaust gases from the combustion chamber 163 to anoutside location.

A cylinder head cover 170 is attached to the cylinder head 160 toenclose one or more camshafts (not shown). The camshafts (not shown)preferably are journaled on the cylinder head 160. The camshafts (notshown) actuate the intake and exhaust valves at speeds that aregenerally in proportion to the engine speed. Other suitable methods ofactuating the valves also can be used.

An upper section of the illustrated engine unit 148 includes thecylinder block 158, the cylinder head 160 and the cylinder head cover170. The upper section at least in part extends rearward beyond theimaginary rear, generally vertical plane 86 (and 86A or 86B).

A lower section of the engine unit 148, which is the balance of theengine unit 148, comprises a crankcase 174, which closes a lower end ofthe cylinder bore (not shown). A crankshaft 176 preferably is joumaledwithin the crankcase 174 and is coupled with the piston (not shown) inany suitable manner. In the illustrated arrangement, the crankshaft 176extends generally transverse to a direction of travel of the vehicle butother orientations also can be used. The reciprocal movement of thepiston results in rotation of the crankshaft 176. The crankshaft 176preferably drives the camshafts via a camshaft drive mechanism.

The crankcase 174 also houses an input shaft for a shiftable portion ofthe transmission 144. The input shaft is positioned forward of thecrankshaft 176. The lower section of the engine unit 148 also comprisesa V-belt housing 178, which is positioned next to the crankcase 174 inthe illustrated arrangement. Moreover, in the illustrated arrangement,the V-belt housing 178 is defined on the left-hand side of the crankcase174. The V-belt housing 178 houses the V-belt transmission mechanism(e.g., continuously variable transmission). Thus, the lower section ofthe engine unit 148 (which comprises at least the crankcase 174 and theV-belt housing 178) also defines, at least in part, a transmissionhousing 180. The transmission 144 will be described in greater detailbelow.

With reference to FIGS. 1-4, the illustrated air intake system 164extends forward to a location under the hood 120 from the intake ports162 of the engine 142. The intake system 164 preferably comprises an aircleaner unit 182 and an air delivery conduit 183 which is formed withthe remainder part of the intake system 164 other than the air cleanerunit 182. The air delivery conduit 183 preferably includes an air intakeduct 184 and a throttle body or carburetor 186. The illustrated airintake duct 184 includes an accumulator or plenum chamber 188.

With reference to FIG. 3, the throttle body 186 in the illustratedembodiment is connected to the intake ports 162 through an air intakeconduit 192. The throttle body 186 comprises a throttle valve 194 thatregulates a rate of airflow amount delivered to the combustion chamber163. The throttle valve 194 preferably is a butterfly valve andgenerally is joumaled for pivotal movement. The level of airflow dependson an angular position of the throttle valve 194—when the throttle valveis closed or substantially closed, minimal air flow results, while whenthe throttle valve is opened or substantially opened, maximum air flowresults.

An accelerator pedal or control member 196 (FIG. 4) preferably isdisposed at a front end of the floorboard 50 for pivotal movement tocontrol the position of the throttle valve 194. A throttle cableconnects the accelerator pedal 196 to the throttle valve 194. The driverthus can control the throttle valve 194 by adjusting an angular positionof the accelerator pedal 196 with his or her own foot 198. Normally, thegreater the throttle valve 194 opens, the higher the rate of airflowamount and the higher the engine speed. Other suitable mechanisms andelectronic connections also can be used to transmit operator demand tothe throttle valve or engine.

The throttle body (e.g., the carburetor) 186, which functions as acharge former, preferably also has a fuel measurement mechanism thatmeasures an amount of fuel mixed with the air in accordance with therate of airflow. Because of this fuel measurement mechanism, air/fuelration supplied to the engine can be controlled and/or optimizeddepending upon engine operating conditions. The fuel is delivered to thethrottle body 186 from a fuel tank (not shown) that can be suitablymounted and suitably position on the frame 32.

Other charge formers such as, for example, a fuel injection system canbe used. The fuel injection system has a fuel injector that isconfigured to spray fuel directly into the combustion chamber 163 orinto a portion of the air intake system downstream of the throttlevalve. An engine control unit (ECU) can control the amount of furlinjected, for example, in accordance with the airflow rate.

With reference to FIGS. 1 and 2, the accumulator 188 can be coupled withan inlet of the throttle body 186. The accumulator 188 generally forms aportion of the intake duct 184 but provides a larger volume, which isdue to a larger cross-sectional flow area, than the rest portion of theintake duct 184 to temporarily accumulate air delivered to the throttlebody 186. Such a construction allows air to accumulate before deliveryto the throttle body 186. The accumulator 188 is useful to expeditedelivering of the air to the combustion chamber when the demand onengine load rapidly increases. As best shown in FIG. 1, the accumulator188 generally has an arcuate configuration. Such a constructionadvantageously smoothens the delivery of air to the engine. Furthermore,because the accumulator 188 has a relatively large volume and isdisposed next to the throttle body 186, the intake efficiency of theinduction system is greatly improved. That is, sufficient air can bequickly supplied to the engine even when the engine is being operated ata relatively high engine speed.

In the illustrated arrangement, the air intake conduit 192, the throttlebody 186 and the accumulator 188 together extend forwardly of the enginewithin a region defined between the seats 68. Upper portions of thethrottle body 186 and the accumulator 188 preferably are positionedslightly higher than the top ends 82A of the seat cushions 72. Aforward-most portion of the accumulator 188 turns downward at or justforward of the forward end of the seat assemblies.

Because of this arrangement, the throttle body 186 and at least aportion of the accumulator 188 are interposed between the seatassemblies and are positioned within, or just adjacent to, the space 70.Thus, the throttle body 186 and the accumulator 188 are positionedwithin a protective region of the vehicle that is located higher than alowermost surface of the frame assembly or the floorboard 50. Suchpositioning reduces the likelihood that dirt and other road debris thatmay be kicked up underneath the vehicle will damage the throttle body186 or the accumulator 188. Such placement also facilitates servicing ofthese components and protects these components from water damage whilefording a stream, a mud bog or the like.

The illustrated accumulator 188, which is positioned within the mostdownstream portion of the illustrated intake duct 184, ends above alowermost surface defined by the rear frame section 38. The balance ofthe air intake duct 184, which has a smaller volume or cross-sectionalarea than the accumulator 188, preferably comprises a downstream section200, a middle section 202 and an upstream section 204, which are providea contiguous air flow path in the illustrated embodiment. The downstreamsection 200 extends downwardly from the accumulator 188 to a lowermostportion of the rear frame section 38. The middle section 202 extendsforwardly in a generally horizontal direction from a lower end of thedownstream section 200.

With reference to FIG. 4, in the illustrated arrangement, the middlesection 202 extends through a tunnel defined by the projection 52 of thefloorboard 50. Because of this arrangement, the middle section 202advantageously is positioned higher than the horizontal section 51 ofthe floorboard 50, which greatly reduces the likelihood of damage fromrocks, sticks, road debris or the like. Furthermore, the driver and/orthe passenger are able to maintain a good riding body position becausethe horizontal section 51 is positioned generally vertically lower thanthe middle section 202. Moreover, the illustrated arrangementcontributes to a lower center of gravity for the off-road vehicle 30because the height of the seats 68 does not need to be increased toaccommodate the middle section 202 or another portion of the airinduction system.

The middle section 202 preferably ends at a location close to the frontframe section 36. The upstream section 204 extends generally verticallyupward from the middle section 202. In addition, the upstream section204 preferably is positioned within a space defined below the hood 134.To increase the protection from ingestion of water, the forward-mostportion of the upstream section 204 extends forward and slightlydownward along a lower surface of the hood 134. Because the hood 120inclines downwardly and forwardly, an upstream end portion 204 a of theupstream section 204, which is located next to the air cleaner unit 182,turns upwardly and is positioned higher than at least an air outlet portof the air cleaner unit 182 which opens at a rear end 205 of the aircleaner unit 182.

The air cleaner unit 182 preferably is attached to the upstream end ofthe intake duct 184 and extends generally along the lower surface of thehood 134. The illustrated air cleaner unit 182 has a relatively largevolume and has a cleaner element therein. The air cleaner unit 182 alsohas an air inlet port that opens at a front end 206 of the cleaner unit182. The inlet port preferably is positioned at least higher than therespective top ends 56 a, 58 a of the wheels 56, 58 and more preferablyhigher than the top surfaces 72 a of the seat cushions 72. Because ofthis arrangement, water is not likely to enter the air cleaner unit 182even when the ATV 30 travels through water streams, mountain torrents ormuddy pools. Ambient air is drawn into the air cleaner unit 182 throughthe air inlet port and passes through the filtration element such thatforeign substances such as, for example, dust, mud or water can besubstantially removed from the air that is being introduced into theengine.

The air, which has been cleaned in the cleaner unit 188, flows to theaccumulator 188 through the rest part of the intake duct 184. Theairflow amount is regulated by the throttle valve 194 in the throttlebody 186. Simultaneously, an amount of fuel is measured by the fuelamount measurement mechanism in the throttle body 186 in response to theair amount. An air/fuel charge that has a proper air/fuel ratio isformed and is delivered to the combustion chamber 163 when the intakevalves open the intake ports 162. The air/fuel charge is ignited by anignition system (not shown) and bums within the combustion chamber 163.The burning of the charge causes expansion of the gases and increasedpressure that results in movement of the piston 159. The crankshaft 176is rotated within the crankcase 174 by the movement of the piston 159.

With reference to FIG. 10, a modified air intake system 164A can have anair cleaner unit 182A that is directly coupled with the throttle body186. The devices, units, components, members and portions thereof thathave been already described above are assigned with the same referencenumerals and will not be repeatedly described. Also, similar devices,units, components, members and portions thereof are assigned with thesame reference numerals with the letter “A” and will not be described indetail.

At least a portion of the air cleaner unit 182A is positioned in thespace 70 defined by the seats 68. The air cleaner unit 182A preferablyhas an air inlet port 182Aa that extends upward from a rear top surfaceof the unit 182A. The illustrated inlet port 182Aa preferably ispositioned higher than the top surfaces of the respective seat cushions72 and more preferably higher than a top surface of the throttle body186.

With reference back to the embodiment illustrated in FIGS. 1-3, theburnt charge, i.e., exhaust gases are discharged through the exhaustsystem 168. The illustrated exhaust system 168 preferably comprises apair of exhaust conduits 208 and a muffler 210. The exhaust conduits 208are coupled with the respective exhaust ports 166 and extend generallyrearward. The exhaust conduits 208 extend generally parallel to eachother. Preferably the exhaust conduits 208 have a wavy shape thatserpentines up and down, as shown in FIGS. 1 and 2. Rearward ends of theexhaust conduits 208 preferably extend beyond a rear end of the rearframe section 38. The muffler 210 is coupled with the rear ends of theexhaust conduits 208.

The muffler 210 preferably has a cylindrical shape. A center axis of themuffler 210 preferably extends in a generally transverse directionrelative to the longitudinal center plane LC of the frame 32. Themuffler 210 has a relatively large volume to reduce exhaust energy andnoise. An outlet port 212 can be formed at a side surface, which is on aleft-hand side in the illustrated embodiment. Other arrangements alsocan be used. The exhaust gases flow through the exhaust conduits 208 andare discharged through the outlet port 212 of the muffler 210.

Because the exhaust system 168 in the illustrated embodiment has therelatively long exhaust conduits 208, the exhaust energy can besufficiently reduced. On the other hand, however, the muffler 210, whichhas a relatively large weight, is disposed at the end of the frame 32.

With reference to FIGS. 11 and 12, a modified exhaust system 168A caninclude a muffler 210A that is disposed at a location closer to amidpoint of the frame 32. The devices, units, components, members andportions thereof that have been already described above are assignedwith the same reference numerals and will not be repeatedly described.Also, similar devices, units, components, members and portions thereofare assigned with the same reference numerals with the letter “A” andwill not be described in detail.

The muffler 210A in this modified embodiment preferably is disposeddirectly behind the engine unit 148 and is affixed to the rear framemembers 46. An outlet port 212A of the muffler 210A is positioned on theright-hand side thereof.

With reference to FIGS. 1, 3 and 5, the change speed mechanism 144 b andthe V-belt transmission mechanism 144 a together have a common outputshaft 216. The output shaft 216 extends generally parallel to thecrankshaft 176 at a location in front of the crankshaft 176. The outputshaft 216 preferably extends through the crankcase 174 and the V-belthousing 178 and is journaled for rotation relative to these components.Because of this arrangement, the output shaft 216 is positioned at alocation generally between the front wheels 56 and the crankshaft 176.In other words, the crankshaft 176 is positioned between the outputshaft 216 and the rear wheels 58.

The crankshaft 176 extends into the V-belt housing 178 and carries adrive pulley 218. The output shaft 216 carries a driven pulley 220. Thedrive and driven pulleys 218, 220 both comprise an axially fixed pulleymember and an axially movable pulley member that is movable along therespective axis of the crankshaft 176 or the output shaft 216. Together,the pulley members form a V-shaped valley that expands and contractswith changes in engine speed.

An endless transmitter (e.g., a belt or a chain) 222 is wound around thedrive pulley 218 and the driven pulley 220. In the illustratedembodiment, the transmitter 222 is a V-type belt and has aV-configuration in section. Normally, the movable pulley member of thedrive pulley 218 is urged to stay apart from the fixed pulley member bythe bias force of a bias member such as, for example, a spring. Themovable pulley member of the driven pulley 220 is urged to stay close tothe fixed pulley member by the bias force of a bias member such as, forexample, a spring.

Each movable pulley member can move axially against the bias force by aclutch mechanism which is provided on either the pulley 218, 220. Theclutch mechanism acts by centrifugal force created when the crankshaftor output shaft turns at a speed higher than a preset speed. The changein diameter of one pulley causes a corresponding change in the otherpulley. Thus, both diameters of the drive pulley 218 and the drivenpulley 220 vary to automatically change the transmission ratio betweenthe drive pulley 218 and the driven pulley 220 normally in response tothe engine speed.

Friction occurs when the belt 222 runs on the pulleys 218, 220, and suchfriction produces heat that can deteriorate the belt 222. In order toinhibit the heat from deteriorating the belt 222, the transmission 144has a cooling system that preferably introduce ambient air into thev-belt housing 178 and discharges the air to an external locationoutside of the housing 178.

With reference to FIGS. 1-3 and 5-9, the V-belt housing 178 preferablyhas an air inlet port 226 at a rear end and an air outlet port 228 at afront end. An air inlet duct 230 is coupled to the inlet port 226, whilean air outlet duct 232 is coupled to the outlet port 228. A downstreamend 230 a of the inlet duct 230 is joined to the inlet port 226 of theV-belt housing 178. The inlet duct 230 has a horizontal portion 230 band a vertical potion 230 c.

The horizontal portion 230 b extends generally rearward from thedownstream end 230 a. In the illustrated embodiment, the air inlet port226 of the V-belt housing 178 is positioned in front of the imaginaryrearward, generally vertical plane 86 (FIG. 3) that includes therearmost end 80 of the seat 68. Thus, a large part of the horizontalportion 230 b is positioned between the seat assemblies. The verticalportion 230 c extends generally upward from the horizontal portion 230 bto a location generally behind the seat back 74, on the left-hand sidein the illustrated embodiment. Preferably, the vertical portion 230 cgenerally extends entirely behind the imaginary rearward, generallyvertical plane 86 (FIG. 3).

The inlet duct 230 preferably has an inlet opening 233 at its upstreamend. The inlet opening 233 faces forward and is disposed at the upperend of the inlet duct 230. The inlet opening 233 preferably ispositioned at almost the same elevation as the top surfaces 72 a of theseat cushions 72. In the illustrated embodiment, the inlet opening 233is positioned slightly higher than the recessed portions 72 aR of thetop surfaces 72 a. In this position, the inlet opening 233 canefficiently draw the ambient air that flows generally between the seats68.

Cooling air is introduced into the V-belt housing 178 through the inletduct 230 and the air inlet port 226 when the crankshaft 176, the outputshaft 216 and the drive and driven pulleys 218, 220 rotate. In somearrangements, one or both of the pulleys can be provided with fan bladesto help induce higher speed air flow as the engine speed increases.Other embodiments can provide a ram air type of air flow. Havingcirculated with the belt chamber of the transmission, the air then isdischarged through the outlet port 228 and the outlet duct 232.

In one variation, as shown in FIG. 6, a modified inlet duct 230A canextends toward a location almost the same elevation of the top end ofthe seat backs 74 and has an inlet opening 233A that is directedrearward. As so arranged, the inlet opening 233A can advantageously drawthe air that is not heated by the engine 142.

The outlet duct 232 preferably has a vertical portion 232 b and ahorizontal portion 232 c. A bottom of the illustrated vertical portion232 b slightly turns rearward toward the outlet port 228 of the V-belthousing 178. An upstream end 232 a, which is a lower distal end of theoutlet duct 232, is joined to the outlet port 228 of the V-belt housing178. The vertical portion 232 b extends generally upward from theupstream end 232 a in front of the V-belt housing 178 toward a locationhigher than a top end of the V-belt housing 178. The horizontal portion232 c preferably defines an uppermost portion of the outlet duct 232.The horizontal portion 232 c extends rearward from the vertical section232 b and generally along a bottom surface of one of the seat cushions72, on the left-hand side in the illustrated embodiment. In other words,the horizontal portion 232 c extends close to the seat cushion 72 andgenerally at the same level as to top of the seat cushions 72. Almostthe entire body of the horizontal portion 232 c lies concealed betweenthe seat assemblies. The outlet duct 232 preferably has an outletopening 234 at its downstream end. The outlet opening 234 preferably isdirected rearward. The illustrated outlet opening 234 is positionednearly to the rear end of the associated seat cushion 72.

As best shown in FIGS. 8 and 9, the horizontal portion 232 c of theoutlet duct 232 in the illustrated embodiment has a configurationcorresponding to a configuration of the associated seat cushion 72.Preferably, the seat cushion 72 has a slant surface 72 a on its sidesuch that the seat cushion 72 becomes narrower toward a bottom end froma top end. The horizontal portion 232 c of the outlet duct 232 generallyhas a triangular shape in section with its hypotenuse extending next tothe slant surface 72 a of the seat cushion 72. Thus, the seat cushion 72and the horizontal portion 232 c of the outlet duct 232 can nesttogether.

As thus constructed, the ambient air is introduced into the V-belthousing 178 through the inlet duct 230 and is discharged through theoutlet duct 232 which the pulleys 218, 220 rotating within the V-belthousing 178. The airflow through the housing 178 prevents the heat frombuilding and thus keeps the belt 222 and the pulleys 218, 220 relativelycool. Belt deterioration due to heat this is reduced and/or slowed.

Because of the arrangement described above, both the inlet opening 233of the inlet duct 230 and the outlet opening 234 of the outlet duct 232are positioned at elevations higher than the respective top surfaces 56a, 58 a of the wheels 56, 58. Thus, even if the wheels 56, 58 aresubmerged during use, water will not enter the V-belt housing 178.

The outlet opening 234 of the outlet duct 232 is directed rearward atnearly the rear ends of the seat cushions 72 as described above. Thenoise in the V-belt housing 178 is channeled rearward and is hardlyaudible to the driver and/or the passenger. Also, because the inletopening 233 of the inlet duct 230 and the inlet opening 233A of themodified inlet duct 230A are positioned behind the seat backs 74, anynoise associated with the airflow into the intake duct generally willnot disturb the driver and/or the passenger. Moreover, further isolationof driver/passenger from such noise is achieved with a rearward facinginlet opening, such as the inlet opening 233A, shown in FIG. 6.

Also, the illustrated horizontal portion 232 c of the outlet duct 232does not lessen the appearance of the off-road vehicle 30, because thehorizontal portion 232 c lies generally concealed between the seatassemblies. In addition, a large part of the horizontal portion 232 ccan be placed under one of the seat cushions 72 because of itsconfiguration which corresponds to the slant surface 72 a of the seatcushion 72. This feature is useful not only for appearance but also tomake the off-road vehicle 30 compact.

With reference to FIGS. 1-3 and 5, the engine output that has beentransferred to the output shaft 216 through the V-belt mechanism istransferred to the drive mechanism 146 through the change speedtransmission mechanism. This mechanism preferably is configured toprovide a parking state, a high speed forward state, a neutral state, alow speed forward state, and a reverse state. The mechanism preferablycomprises a suitable gear train that allows an operator to select amongat least the above-mentioned operating states. A bevel gear assembly 236can be coupled with the mechanism.

The mechanism also comprises a shift lever unit 240 that extends fromthe crankcase 174. The shift lever unit 240 preferably is connected tothe rest of the switchover mechanism within the crankcase 174 through asuitable linkage (not shown). The shift lever unit 240 preferably isplaced generally within the space defined between the seats 68. Theillustrated lever unit 240 is positioned generally at the forward-mostportion of the space. Such placement facilitates ease of use.

The shift lever unit 240 preferably comprises a lever 244 and a levercover 246. The lever 244 preferably is affixed to the frame 32 directlyor indirectly for pivotal movement around a fulcrum. In one variation,the shift lever unit 240 can comprise a lever that moves axially. Thedriver thus can control the change speed mechanism in the crankcase 174and vary the transmission operating state among at least the parkingstate, the high speed forward state, the neutral state, the low speedforward state, and the reverse state by operating the lever 244.

Because of the advantageous configuration of the drive train relative tothe shift lever unit 240, the shift lever unit 240 is positioned closeproximity to the change speed mechanism of the transmission 144. Thelinkage thus can be short enough to make the switchover mechanismcompact and also to improve the feeling that the driver might have whenoperating the shift lever unit 240.

The output of the change speed mechanism 144 b is transferred to thedrive system 146 through the bevel gear 236. The forward driveshaft 150of the drive system 146 is pivotally coupled with a forward differentialinput shaft (not shown) of the forward differential gear unit 119. Theforward differential input shaft is connected to the front wheels 56through a differential mechanism formed within the forward differentialgear unit 119. The rear driveshaft 152 is coupled with a reardifferential input shaft (not shown) of the rear differential gear unit154. The rear differential input shaft is coupled with the rear wheels58 through another differential mechanism formed within the reardifferential gear unit 154.

The engine unit 148 can have systems, devices, components and membersother than those described above. For example, the illustrated engine142 employs a starter motor that starts the engine 142.

The off-road vehicle 30 preferably has other devices, components andmembers. For example, the differentials can be selectively lockable suchthat the differential function can be eliminated on demand. Moreover, abrake system can be provided to slow or stop rotation of the wheels 56,58 or another drive train component (e.g., the driveshafts). A brakepedal 270 (FIG. 5) can be disposed next to the accelerator pedal 196 andcan be connected to brake units that are coupled with the wheels 56, 58.In some arrangements, the brake units can comprise disk brakeconfigurations. The driver thus can stop the off-road vehicle 30 byoperating the brake pedal 270.

In the illustrated arrangement, the engine 142 is located generallyrearward of the change speed mechanism including the output shaft 216.Moreover, the engine is positioned generally rearward of, and lowerthan, the seating area. Thus, heat generated by the engine 142 can besubstantially isolated from the driver and/or the passenger, andparticularly isolated from the feet of those persons both when seatingand when mounting or dismounting from the vehicle. In addition, thecylinder block 158, the cylinder head 160 and the cylinder head cover170 in this arrangement generally are directed rearward and arepositioned generally rearward of the occupants. Thus, it is veryunlikely that the engine heat will affect the occupants of the vehicle.

The exhaust system 168 carries a great deal of heat as well while theintake system 164 and the charge former, e.g., the throttle body 182,generally do not generate or conduct much heat. The intake system 164and the charge former are generally protected from heat carried by theexhaust system 168 because the exhaust system 168 is positioned oppositeto the intake system 164 in the illustrated arrangement. Thus, theengine heat and the exhaust heat can be generally isolated from theintake system 164 during forward operation of the off-road vehicle 30.The temperature of the intake air, therefore, is not greatly affected bythe heat generated during operation of the off-road vehicle 30 andengine output efficiency can be kept in good condition. Along theselines, placement of a radiator preferably is generally below the airintake such that heat generated in the region of the radiator does notadversely affect engine performance through heating of the air inductedinto the engine.

Furthermore, in the illustrated intake system 164, the intake system 164generally does not extend along a heat generating or conducting surfaceof the engine 142. Thus, the engine heat is generally isolated from theintake system 164 in this arrangement. Also, the illustrated air cleaner188 is greatly spaced from the engine 142. As such, any air that isheated by the engine 142 and the exhaust system 168 will not be drawninto the air intake system 164, which improves the engine outputefficiency. Additionally, due to the elevated nature of the air inletand air cleaner 188, water also is very unlikely to be drawn into theintake system 164. Furthermore, because the air cleaner 188 ispositioned below the hood 134, water is unlikely to splash its way intothe air cleaner.

As illustrated, the exhaust conduits 208 extend along a relatively lowerportion of the off-road vehicle 30 in the illustrated arrangementbecause the exhaust conduits 208 are directed generally downward andrearward instead a wrapping around from a forward or lateral surface ofthe engine. The exhaust conduits 208, thus, are sufficiently spacedapart from the driver and/or the passenger. As a result, the seats 68can be positioned closer to the engine 142, which allows a narroweroverall construction for the vehicle or a closer mounting of the splitseats 68.

Although the present invention has been described in terms of a certainpreferred embodiment, other embodiments apparent to those of ordinaryskill in the art also are within the scope of this invention. Thus,various changes and modifications may be made without departing from thespirit and scope of the invention. The scope of the present invention isintended to be defined only by the claims that follow.

1. An off-road vehicle comprising a frame, at least one seatingarrangement including at least first and second seating areas, each ofthe first and second seating areas being configured to support a rider,a plurality of wheels arranged to support the frame, an internalcombustion engine powering at least one of the wheels, and an air intakesystem arranged to supply air to the engine for combustion at a locationabove an uppermost surface of the wheels, the air intake system havingan air inlet and an air cleaner through which ambient air enters theintake system, the air inlet and the air cleaner positioned higher thanthe uppermost surface of the wheels, and an air intake duct extendingrearwardly to the engine, the air intake duct extending from the aircleaner, then to at least a first portion of the air intake ductpositioned lower than the uppermost surface of the wheels, and at leasta second portion of the air intake duct being disposed between the firstand second seating areas.
 2. The off-road vehicle as set forth in claim1, wherein the air cleaner is configured to clean the air that entersthrough the air inlet.
 3. The off-road vehicle as set forth in claim 2,further comprising two seat assemblies disposed side by side on theframe, at least a portion of the air cleaner is positioned between theseat assemblies.
 4. The off-road vehicle as set forth in claim 1,wherein the air intake system delivers supply air to at least onecombustion chamber of the engine.
 5. The off-road vehicle as set forthin claim 1, wherein the first and second seating areas comprise firstand second seats separate from each other.
 6. An off-road vehiclecomprising a frame, at least one seating arrangement including at leastfirst and second seating areas, each of the first and second seatingareas being configured to support a rider, a plurality of wheelsarranged to support the frame, an internal combustion engine powering atleast one of the wheels, and an air intake system arranged to supply airto the engine for combustion at a location above an uppermost surface ofthe wheels, the air intake system having an air inlet through whichambient air enters the intake system, the air inlet positioned higherthan the uppermost surface of the wheels, an air intake duct extendingrearwardly to the engine, at least a first portion of the air intakeduct being positioned lower than the uppermost surface of the wheels,and at least a second portion of the air intake duct being disposedbetween the first and second seating areas, and a hood configured tocover at least a front portion of the frame, the air inlet disposedbelow the hood.
 7. An off-road vehicle comprising a frame, at least oneseating arrangement including at least first and second seating areas,each of the first and second seating areas being configured to support arider, a plurality of wheels arranged to support the frame, an internalcombustion engine powering at least one of the wheels, and an air intakesystem arranged to supply air to the engine for combustion at a locationabove an uppermost surface of the wheels, the air intake system havingan air inlet through which ambient air enters the intake system, the airinlet positioned higher than the uppermost surface of the wheels, an airintake duct extending rearwardly to the engine, at least a first portionof the air intake duct being positioned lower than the uppermost surfaceof the wheels, and at least a second portion of the air intake ductbeing disposed between the first and second seating areas, and an aircleaner configured to clean the air that enters through the air inlet,wherein at least a portion of the air cleaner is positioned below thehood.
 8. An off-road vehicle comprising a frame, a plurality of wheelsarranged to support the frame, an internal combustion engine powering atleast one of the wheels, and an air intake system arranged to supply airto the engine for combustion at a location above an uppermost surface ofthe wheels, the air intake system having an air inlet and an air cleanerthrough which ambient air enters the intake system, the air inlet andthe air cleaner positioned higher than the uppermost surface of thewheels, and an air intake duct extending from the air cleaner, then toat least a portion of the air intake duct positioned lower than theuppermost surface of the wheels, then to the engine, and at least twoseat assemblies disposed side by side on the frame, the air inletpositioned between the seat assemblies in a top plan view of thevehicle.
 9. An off-road vehicle comprising a frame, a plurality ofwheels arranged to support the frame, a hood configured to cover atleast a first portion of the frame, an internal combustion enginepowering at least one of the wheels, an air intake system arranged tosupply air to an intake port of the engine for combustion, the airintake system comprising an air cleaner configured to clean the air andan air delivery conduit arranged to deliver the air in the air cleanerto the engine, the air cleaner disposed below a central portion of thehood and above the floorboard, the engine being disposed on a secondportion of the frame, the second portion being spaced apart from thefirst portion, a third portion of the frame extending between the firstand second portions, the third portion including a floorboard, and atleast a portion of the air delivery conduit extending below thefloorboard, the intake port being disposed above the floorboard.
 10. Theoff-road vehicle as set forth in claim 9, wherein the engine has an airintake port communicating with a combustion chamber of the engine andthe air delivery conduit connects the air cleaner to the air intakeport.
 11. The off-road vehicle as set forth in claim 10, wherein the airdelivery conduit comprises a throttle body that has a throttle valve toregulate an amount of air passing to the combustion chamber.
 12. Theoff-road vehicle as set forth in claim 11, wherein the air deliveryconduit includes an accumulator disposed between the throttle body andthe balance of the intake duct, an inner diameter of the accumulator isgreater than an inner diameter of the rest of the delivery conduit. 13.The off-road vehicle as set forth in claim 9, additionally comprising aseat unit disposed on the second portion of the frame, the engine andthe seat unit positioned next to each other.
 14. The off-road vehicle asset forth in claim 13, wherein the seat unit comprises at least two seatassemblies placed side by side, the engine at least in part isinterposed between the seat assemblies.
 15. The off-road vehicle as setforth in claim 14, wherein each one of the seat assemblies comprises aseat and a pedestal that supports the seat.
 16. The off-road vehicle asset forth in claim 9, wherein at least a portion of the air deliveryconduit is positioned higher than the air cleaner.
 17. The off-roadvehicle as set forth in claim 16, wherein at least a portion of the aircleaner is positioned higher than the wheels.
 18. The off-road vehicleas set forth in claim 9, wherein at least a portion of the air cleaneris positioned higher than the wheels.
 19. The off-road vehicle as setforth in claim 18 additionally comprising a seat unit that defines asurface onto which a driver or passenger of the vehicle sits, thesurface positioned higher than the wheels, and at least a portion of theair cleaner is positioned higher than the surface.
 20. The off-roadvehicle as set forth in claim 19, wherein the air cleaner has an airinlet and at least the air inlet is positioned higher than the surface.21. The off-road vehicle as set forth in claim 18, wherein the aircleaner has an air inlet and at least the air inlet is positioned higherthan the wheels.
 22. The off-road vehicle as set forth in claim 9,wherein the hood additionally covers at least one of the wheels.
 23. Anoff-road vehicle comprising a frame, a plurality of wheels arranged tosupport the frame, at least one seat supported by the frame, an internalcombustion engine powering at least one of the wheels, and an air intakesystem arranged to supply air to the engine for combustion, the airintake system comprising an air cleaner configured to filter the air,the seat being disposed in a fore to aft direction on the vehicle suchthat the air cleaner lies forward from the seat and at least a portionof the engine lies behind the seat.
 24. The off-road vehicle as setforth in claim 23, wherein the air intake system delivers supply air toat least one combustion chamber of the engine.
 25. The off-road vehicleas set forth in claim 23, wherein at least a portion of one combustionchamber of the engine is positioned rearwardly of the seat.
 26. Theoff-road vehicle as set forth in claim 23, wherein the entire aircleaner is disposed forward from the forward-most edge of the seat.